Do whatever feels best for your company at the moment.

Monolith - Easier and straightforward, less thought on architecting the puzzle, and more about solving the issue at hand. Later down the line, this will cause pain points, should you be able to justify that pain with momentary momentum then this is the option for you.

Multi-tier - Decoupled monolithic application, generally happens after second iteration of a monolithic application.

Microservices - Modular, and requires more thought behind the interactions and architecture of the system. More thought should be put into also the deploy, and scaling of the system as well. Eventually you will have to do this. It is very obvious this is the natural progression of things as something grows.